Sweeping the summer skies with APM's 7.1" F/6 Refractor

Saturday night I was out with a group of friends until after midnight using my lightweight (26 pounds) 7.1" TMB designed APM 180 F/6. This is an ideal time of the year to get out and observe the summer skies, and the Milky Way directly overhead, at least at my location in California. The Large Rich Field Refractor is ideal for sweeping large open areas of the night skies, especially when matched to my Losmandy G11 with a 12” extension pier.

We had nearly perfect seeing conditions and perfect transparency, with a low of 60 degrees F, making for an excellent night of summer observing.

Even without filtering, the Veil Nebula was visible last night with the big 180mm achromat. Using a Lumicon OIII filter in my 41 Panoptic at 26x and 2.6 deg actual field of view. All 3 segments of the Veil jumps out at you, the western arch, the central filaments, and the eastern arch. Despite the large field of view using the 41 Pan Optic, all 3 segments of the Veil were not all visibl at one time, though it was close. My Celestron 150R 6" F/5, I recently sold, was capable of just barely capturing all three segments of the Veil in one field of view however.

I tried observing the crescent nebula, but the skies were still not dark enough with my large refractor, though the North America nebula came through nicely, especially around the Gulf of Mexico region.

Another object that came through beautifully with the large refractor was the Helix Nebula. This again, even without filtering, was a very eerie transparent aberration in the eyepiece. Using a UHC filter which seemed to help more than an OIII filter with my 17 Nagler, the Helix came alive and the large oval with a dark center clearly stood out like a huge smoke ring low in the east. The UHC filter gave a better visual effect since it didn't darken the entire view as much as the 0III did.

A few other objects I observed which really were impressive were the Double Cluster in Perseus. Using my 31 Nagler at 35x, both clusters were full of beautiful star fields including a few very obvious red giants, which some of the smaller 4" refractors were unable to detect.

M81 and M82, side by side, and the Owl nebula, (M97) and M108 were also excellent objects to observe using a 26mm Nagler with no filtering, at 41x before the big dipper dipped low in the west. The Draco Triplets were also stunning last night, using my 14mm Meade Ultra wide 82 deg. 2" eyepiece at 77x, the highest magnification I used all night.

Once M31 was high enough in the sky, it was also a spectacular object to look at using my 26mm Nagler, again at 41x, The entire galaxy fanned across the entire field of view, showing not only the brighter M32 galaxy, but also the larger but dimmer M110, easily seeing all 3 galaxies in one field of view.

Kembles Cascade asterism was also viewable in one entire field of view, using my 41 pan optic. The large string of stars ending with NGC 1502 were all visible at 26x. Higher magnification using my 17 Nagler revealed the small open NGC cluster showed dozens of tiny glistening stars.

Over Sagittarius, The Eagle and Swan Nebula were both visible in one field of view using my 41 Pan Optic also. Both were beautiful without filtering however using a UHC filter brought out more of the nebulous structure of both objects. My friend FSQ was also able to also capture M24 in the same field of view using his 41 Pan Optic at about 13x. There were also numerous small globular clusters and open clusters throughout the entire region of Sagittarius and Scorpio, you can catch just by sweeping the skies slowly at low power.

The Lagoon and Trifid Nebula were also beautiful at low power using my 26 Nagler (41x) Still using the UHC filter, both stood out beautifully against the back ground stars.

The last object I looked at was the Pleiades. Even though the moon had started to rise, the nebulosity was clearly seen radiating off a few of the stars using my 41 Pan Optic.

Only a handful of these big low power wide field instruments were ever produced due to the level of optical quality both TMB and APM demanded from these optics. Choosing your objects wisely with a large wide field refractor like this will reward you with a perfect night of summer observing.

I keep the tube rings on the scope, and the 14" dovetail. The entire OTA with those attached weight 30 pounds. Thats basically the lifting weight to get the scope on the mount. Its the weight of my C11 OTA or my TOA-130. The OTA itself is 26 pounds. The tray you see between the 12" extension pier and the pier itself is a pizza pan with a hole cut in the middle so the two parts of the pier fit together to hold it in place. Its 1080mm FL, so when the dew shield is retracted, its a very compact scope. I put the handle on top years ago to carry the scope like a suitcase when I'm transporting it. The telrad comes on and off on a dovetail shoe. I also mount a lazer on another dovetail mounted on the OTA you cant see in the photo. It works well with a binoviewer also, you can see attached to the scope in the photo.

...Ralph

sounds wonderful, thanks for the report! would be great to leave the 30x eyepiece in there and just roam.

Back in the day the Jaegers 5" f/5 was popular for the same type of viewing.

So it looks like they only make the 8" f/9 these days - do you know how much the 7" weighs??